The return is needed. It prevents vapor lock by being at the top of the filter so on a hot shutdown the vapors blow back tot he tank rather than vapor locking the gas line. It also has a metered hole so the main center line keeps the pressure right for a BBD carb.
A gent also flipped his filter around and used the smaller return line with it's metered hole in it as a fuel pressure regulator. It gave 1.5 psi at idle and 3 at speed I think:
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com
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